Various heat-developable light-sensitive materials are known. For example, such materials and photographic processes for processing them are described in Bases of Photographic Engineering, Edition of Nonsilver Photography (published by Corona Publishing Co., Ltd., Japan, 1982), pages 242 to 255.
Various methods have been proposed for forming color images by heat development. For instance, U.S. Pat. Nos. 3,531,286, 3,761,270, 4,021,240, Belgian Patent 802,519, Research Disclosure (hereinafter referred to as RD) in September 1975, pages 31 to 32 propose methods for forming color images by reaction of an oxidation product of a developing agent and couplers.
However, since the above-mentioned heat-developable light-sensitive materials for forming color images are of a non-fixing type, silver halides still remain in the processed materials. The silver halides remained in the processed materials cause a serious problem in that, when the processed materials are exposed to strong light or when they are stored for a long period of time, the white background areas in the materials are gradually colored. In addition, the above-mentioned photographic processes generally need a relatively long period of time for developing light-sensitive materials and have a drawback in that the images formed are highly fogged while having a low color density.
In order to overcome the problem and drawback, a method has been proposed in which a diffusive dye is imagewise formed or released under heat and the diffusive dye is transferred to an image-receiving material having therein a mordanting agent in the presence of a solvent such as water, as described in, for example, U.S. Pat. Nos. 4,500,626, 4,483,914, 4,503,137, 4,559,920, and JP-A-59-165054 (the term "JP-A" as used herein means an "unexamined published Japanese patent application).
However, this method is not satisfactory because the temperature for development is still high and the storability of raw stock is not sufficient. Different methods have been disclosed in JP-A-59-218443, JP-A-61-238056, JP-A-62-129848 and European Patent 210660A2, in which a light-sensitive material is heat-developed in the presence of a base precursor and a small amount of water thereby transferring a dye to a dye-receiving material. According to these methods, the development is accelerated while the temperature for the development is lowered, and the processing steps are simplified.
Various methods have also been proposed for forming positive color images by heat development. For instance, U.S. Pat. No. 4,559,290 discloses a method in which an oxidized compound having no color image releasing capacity as derived from a so-called DRR compound is, in the presence of a reducing agent or a precursor thereof, reduced with the reducing agent which remains without being oxidized after oxidation of the agent in accordance with the exposed amount of a silver halide by heat development, to thereby release a diffusible dye. U.S. Pat. No. 4,783,396 and JP-A-64-13546 disclose a heat-developing color light-sensitive material having a compound which releases a diffusible dye by the same mechanism as mentioned above, or that is, releases a diffusible dye by reductive cleavage of the N--X bond of the compound (where X is an oxygen atom, a nitrogen atom or a sulfur atom). According to this method, a multilayered, heat-developing color light-sensitive material having, on a support, at least a light-sensitive silver halide, a binder, an electron donor and/or its precursor (preferably having a non-diffusible group), and a compound which may release a diffusible dye when reduced and which itself is non-diffusible is, after having been exposed, heated so that the electron donor is oxidized in accordance with the amount of the silver halide therein while the above-mentioned reusable dye-donating compound is reduced by the electron donor which has remained as it is without being oxidized, thereby releasing a diffusible dye, and the thus-released dye is transferred to a dye-fixing (image-receiving) material having therein a mordanting agent, thereby forming a positive color image on the material.
In general, ordinary silver halide color light-sensitive materials have a multi-layered structure, in which, for example, a panchromatic silver halide emulsion layer sensitive to red light, an orthochromatic silver halide emulsion layer sensitive to green light and, as the uppermost layer, a regular silver halide emulsion layer sensitive to blue light are coated on a support in this order from the side of the support.
In these color light-sensitive materials having the structure mentioned above, the panchromatic silver halide emulsion and the orthochromatic silver halide emulsion are color-sensitized with optical sensitizers which are generally referred to as sensitizing dyes. Such optical sensitizers or sensitizing dyes are sensitive to also the silver halide in the blue-sensitive emulsion layer, they cause color mixing or coloring failure due to the overlapping of the color spectra for the plural color-sensitive layers, after all detracting from the color reproducibility of the light-sensitive material.
In order to evade these problems, for example, a blue light-absorbing filter layer is generally provided between the blue-sensitive silver halide emulsion layer and the green-sensitive silver halide emulsion layer in a color negative light-sensitive material. As such a blue light-absorbing filter layer, for example, used is a layer comprising silver colloid of grains having a grain size of approximately from 0.001 to 0.05 .mu.m or a layer containing a dye that dissolves out in processing solutions or decolors during processing. These methods are described in, for instance, U.S. Pat. Nos. 4,948,717, 4,948,718, 4,940,645 and 4,900,653.
In heat-developable color light-sensitive materials, where the dye-donating compound is a colored one, the layer itself containing this compound acts as a filter layer so that any additional blue light-absorbing filter layer is not always necessary. However, if the dye-donating compound in the material is a colorless coupler or if the extinction coefficient of the material at 500 nm or less is not sufficient, it is desirable to provide a blue light-absorbing filter layer in the material.
However, heat-developing light-sensitive materials cannot have a silver colloid layer such as that mentioned above. This is because silver colloid grains act as physically-developed nuclei in heat-developing light-sensitive materials, resulting in the increase in the fog of the material and the decrease in the color density of the same or causing mixing of colors in the material.
It is not also preferred to incorporate a dye that dissolves out in processing solutions or decolors during development into heat-developable light-sensitive materials. This is because heat-developable light-sensitive materials are generally processed within a short period of time so that the dye cannot often decolor during development and the dye remained in the processed material will be transferred to an image-receiving material to cause stains therein.
Japanese Patent Application No. 5-149713 describes a heat-developable color light-sensitive material containing a solid organic pigment in the light-sensitive silver halide emulsion layer and/or its adjacent layers. The described, heat-developing color light-sensitive material is free from color mixing and coloring failure and therefore has excellent color reproducibility. In this, in addition, no stain is formed.
However, when this material is processed to form a color image thereon, after having been stored under forced conditions, this is often much fogged. (The storing of light-sensitive materials under forced conditions is hereinafter referred to as storing of raw stock.) Where light-sensitive materials are produced, in general, the coating compositions containing the necessary components such as light-sensitive silver halides, etc. are left as they are for several hours. However, when the above-mentioned heat-developing color light-sensitive material is produced and when a coating composition containing a solid organic pigment is left as it is for a while, then large coarse grains are formed in the composition. It has been found that, if the coating composition containing such large coarse grains therein is coated on a support to produce a heat-developing color light-sensitive material and if the thus-produced material is exposed and processed to form an image thereon, the processed material has many non-colored areas having a size of about 0.1 mm or less. In producing light-sensitive materials, one coating machine is often used to produce plural kinds of light-sensitive materials. In such a case, if some components constituting the previous composition remained in the ducts and the like in the machine where coating compositions passes through, the next coating composition will be contaminated by the previous coating composition. Therefore, it is necessary that the components constituting coating compositions do not remain in the ducts and the like in the coating machine. To wash the ducts in the coating machine, it is desirable not to use organic solvents in view of the prevention of environmental pollution. However, it has been found that, when the coating composition containing a solid organic pigment adheres to the ducts in a coating machine in producing the above-mentioned color light-sensitive materials, then it is extremely difficult to wash the contaminated ducts.